Acoustical fuze activator

ABSTRACT

The high ram pressure formed at the stagnation point of a projectile nose in flight is used as a source to drive a fluid oscillator within the projectile. A piezoelectric crystal is connected to the fluid oscillator to produce an electrical current when excited by the oscillator. The resulting current can be used to power the electrical components within the projectile.

United States Patent 1 Campagnuolo et al.

[ ACOUSTICAL FUZE ACTlVATOR [75] Inventors: Carl J. Campagnuolo, Chevy Chase; Leonard Sieracki, Beltsville, both of Md.

The United States of America as represented by the Secretary of the Army, Washington, DC.

Filed: Nov. 18, 1966 Appl. No.: 596,051

Assignee:

US. Cl. 102/70.2 G, 102/81 Int. Cl. F42c 15/00 Field of Search 340/10; 102/70.2, 81,496;

[56] References Cited UNITED STATES PATENTS 2,895,063 7/1959 Morris l02/70.2G

[ Jan. 21, 1975 3,229,638 1/1966 Woolston et a1 l02/49.6 3,271,596 9/1966 Brinkerhoff.... 340/10 3,362,332 1/1968 Campagnuolo 102/81 Primary Examiner--Verlin R. Pendegrass Attorney, Agent, or Firm-Nathan Edelberg; Robert P. Gibson; Saul Elbaum ABSTRACT 9 Claims, 6 Drawing lFigures l l I IO ll 5 l l l4 r z I z ll ACOUSTICAL F UZE ACTIVATOR This invention relates generally to fuze activators for missiles and more particularly to an improved acoustical signal generator which permits a missile fuze to be activated only after the missile has attained a predetermined speed.

In the past, chemical batteries have served as a source of electrical power to activate fuzes or other components in a missile, such as a mortar shell. The present invention is a new approach to the generation of electrical power from an acoustical source. When a shell or small artillery missile flies through the atmosphere, a high ram pressure is formed at the stagnation point of the missile nose. This invention utilizes the ram pressure as a pneumatic source in a fluid oscillator having no moving parts.

Some of the preferred embodiments of the invention are disclosed in detail in the following description and accompanying drawing in which:

FIG. 1 is a schematic diagram ofa portion ofa missile incorporating a pneumatic generator having a single rectangular resonator chamber;

FIG. 2 is a schematic diagram ofa portion ofa missile incorporating a single cylindrical resonator;

FIG. 3 is a schematic diagram of a portion of a missile incorporating two nozzles and two resonators;

FIG. 4 is a schematic diagram ofa portion ofa missile incorporating a pneumatic generator having four nozzles and a single cylindrical resonator; and

FIG. 5 is a schematic diagram ofa portion ofa missile incorporating the improved pneumatic generator and having four nozzles and four cylindrical resonators;

FIG. 6 is a schematic diagram ofa modification applicable to all the preceding figures.

In FIG. 1, a nozzle 10 is formed in the nose 12 of a missile 14. A wedge or splitter 16 is placed directly below the orifice of nozzle 10 and is fixed at itslower end to a piezoelectric crystal 18 which in turn is fixed to the wall of missile 14. Leads 19 are connected to opposite faces of crystal 18.

In operation, when the missile is flying through the atmosphere in the direction indicated by the arrow 20, ram air indicated by the arrow 22 enters nozzle 10 and impinges upon wedge 16. A portion of the air jet is deflected into the rectangular resonator chamber 24 formed by wedge 16 as one wall and crystal 18 as the bottom. When resonance occurs in resonator chamber 24, a high intensity sound is emitted. The frequency of the oscillator formed by resonator 24 and nozzle 10 is directly proportional to the velocity of the jet at the oriflee of nozzle 10 and inversely proportional to the distance 26 between the orifice of nozzle 10 and the top edge of wedge 16.

The frequency generated by the fluid oscillator is known as edge-tone frequency. The dominant frequency of the oscillator is controlled by the size of the cavity of resonator 24. The edge-tone frequency is higher than the resonator frequency, but lower in amplitude, since it interacts with the harmonics of the resonator eigen frequencies. Hence, this type of fluid oscillator is known as an edgetone-resonator oscillator or a ring tone oscillator.

Piezoelectric crystal 18 forms the back wall of the oscillator, and it deflects at the same frequency as the oscillator frequency to produce an electrical voltage also of the same frequency. The electrical power output of the piezoelectric crystal depends upon the size and shape of the crystal. It is to be understood that the crystal may be any other suitable type of electrical transducer. Crystal 18 may also be placed on a diaphragm which is designed to vibrate at the oscillator frequency. With such an arrangement, an output power of up to one watt or higher can be obtained. Such power is generally sufficient to operate the electronic components present in the fuze circuits in shells or missiles.

The pneumatic oscillator may be constructed in such a way so as to trigger only at a predetermined input pressure which in turn would be produced at only a predetermined velocity of the missile relative to the atmosphere. Such a threshold effect. is obtained by varying the size of the resonator chamber 24. The size of the resonator chamber may be varied, for example, by placing crystal 18 on an adjustable mounting means (not shown) which may be moved vertically relative to the wedge 16. With such an arrangement, as the missile or shell 14 flies through the air, the electronic components connected to the output of piezoelectric crystal 18 can remain inactive until a specified shell velocity is achieved, at which time the pneumatic oscillator will trigger and cause the electronic components to operate.

FIG. 2 is a modification of FIG. 1 in that the rectangular resonator chamber 24 is replaced by a cylindrical resonator 27 having a sharp upper rim 28. The fluid jet passing through the three-dimensional nozzle 30 impinges upon the rim 28 to produce a high intensity sound at resonance. The resonant frequency is determined by the length of cylinder 27. A piezoelectric crystal 31 is placed at the back end of cylinder 27 and glued on a thin metal diaphragm 32. Diaphragm 32 may be moved along the axis of the cylinder to change the size of resonating cavity and thereby the resonant frequency.

FIG. 3 is similar to FIG. 1 with the difference that two oscillators are used. Formed in the missile nose are nozzles 34 and 36. Mounted on the wall of the missile are two resonator chambers 38 and 40. The fluid jet passing through nozzle 34 impinges upon wedge 42 and is partially deflected into the resonator chamber 38 to cause the piezoelectric crystal 44 to deflect at resonant frequency. In like manner, the fluid jet passing through nozzle 36 impinges upon wedge 46 and is partially deflected into chamber 40 to cause crystal 48 to deflect at resonant frequency.

FIG. 4 illustrates a missile 50 having four nozzles 52, 54, 56, and 58 spaced 90 apart in the nose of the missile. Supported in the missile beneath the nozzles by suitable means (not shown) is a single cylindrical resonator 60. The four fluid jets passing through the four nozzles each impinge upon a different point of the upper rim 62 of the resonator 60. Such a pneumatic generator produces high intensity tones at very low ram pressures.

FIG. 5 shows a variation of FIG. 4 in which again four nozzles 64, 66, 68 and 70 are mounted in the nose of a missile 72. But here, four separate cylindrical resonators 74, 76, 78 and 80 are each mounted below a different one of the four nozzles so that: the fluid jet passing through each nozzle impinges upon the upper rim of a different one of the resonators.

FIG. 6 illustrates a modification applicable to all the preceding figures. To increase the power output from any of the resonant chambers, the crystal may be mounted on each side of the diaphragm which forms the bottom of the chamber. In FIG. 6, a crystal 82 and a crystal 84 are mounted on opposite sides of the thin metal diaphragm 86.

The improved acoustical signal generator ofthc type described and illustrated herein is capable of replacing the chemical batteries which are presently employed to activate fuzes and other electronic components in a shell or missile. Such a generator has a long shelf life, does not need to be charged and can be built so as not to be affected by shocks and vibrations. Such an oscillator can be built to work at both subsonic and supersonic jet flow velocities. The improved pneumatic generator can be used on any device that flies through the atmosphere, such as airplanes, missiles, engines, helicopters, etc.

While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

What is claimed is: 1. An acoustical signal generator for activating a fuze in a missile moving through a fluid medium comprising: a. fluidic oscillator means in the missile comprising a resonant chamber for generating a fluid vibration signal having a frequency related to the speed of the missile relative to the medium and wherein all elements of the oscillator remain stationary with respect to the missile, b. nozzle means for directing fluid to said resonant chamber, and c. electrical transducer means responsive to said fluid vibration signal to produce an electrical signal for activating said missile fuze. 2. An acoustical signal generator as defined in claim 1 wherein said electrical transducer means comprises a piezoelectric crystal.

3. An acoustical signal generator as defined in claim 1 wherein said fluidic oscillator means comprises an edge tone resonator oscillator means.

4. An acoustical signal generator as defined in claim 3 wherein said edge tone resonator-oscillator means comprises a resonant chamber having a wall member positioned in the path of the fluid jet passing through said nozzle means to produce said fluid vibration signal.

5. An acoustical signal generator as defined in claim 4 wherein said chamber is cylindrical.

6. An acoustical signal generator as defined in claim 4 wherein said resonant chamber further comprises an 7 electrical transducer responsive to the fluid vibration signal to produce an electrical signal proportional thereto.

7. An acoustical signal generator as defined in claim 1 wherein:

a. said nozzle means comprises two nozzles formed in the nose of said missile, and b. said edge tone resonator-oscillator means comprises two edge tone resonator-oscillators each responsive to the fluid jet passing through a different one of said two nozzles. 8. An acoustical signal generator as defined in claim I wherein said nozzle means comprises four nozzles spaced apart so that four corresponding fluid jets each impinge upon a different edge of said edge tone frequency resonator-oscillator means.

9. An acoustical signal generator as defined in claim 8 wherein said edge tone resonator-oscillator means comprises four individual edge tone resonatoroscillators each responsive to the fluid jet passing through a different one of said four nozzles. 

1. An acoustical signal generator for activating a fuze in a missile moving through a fluid medium comprising: a. fluidic oscillator means in the missile comprising a resonant chamber for generating a fluid vibration signal having a frequency related to the speed of the missile relative to the medium and wherein all elements of the oscillator remain stationary with respect to the missile, b. nozzle means for directing fluid to said resonant chamber, and c. electrical transducer means responsive to said fluid vibration signal to produce an electrical signal for activating said missile fuze.
 2. An acoustical signal generator as defined in claim 1 wherein said electrical transducer means comprises a piezoelectric crystal.
 3. An acoustical signal generator as defined in claim 1 wherein said fluidic oscillator means comprises an edge tone resonator oscillator means.
 4. An acoustical signal generator as defined in claim 3 wherein said edge tone resonator-oscillator means comprises a resonant chamber having a wall member positioned in the path of the fluid jet passing through said nozzle means to produce said fluid vibration signal.
 5. An acoustical signal generator as defined in claim 4 wherein said chamber is cylindrical.
 6. An acoustical signal generator as defined in claim 4 wherein said resonant chamber further comprises an electrical transducer responsive to the fluid vibration signal to produce an electrical signal proportional thereto.
 7. An acoustical signal generator as defined in claim 1 wherein: a. said nozzle means comprises two nozzles formed in the nose of said missile, and b. said edge tone resonator-oscillator means comprises two edge tone resonator-oscillators each responsive to the fluid jet passing through a different one of said two nozzles.
 8. An acoustical signal generator as defined in claim 1 wherein said nozzle means comprises four nozzles spaced 90* apart so that four corresponding fluid jets each impinge upon a different edge of said edge tone frequency resonator-oscillator means.
 9. An acoustical signal generator as defined in claim 8 wherein said edge tone resonator-oscillator means comprises four individual edge tone resonator-oscillators each responsive to the fluid jet passing through a different one of said four nozzles. 